This invention relates to a fuel delivery rail assembly for an internal combustion engine, especially for an automotive engine, equipped with a fuel injection system. The fuel delivery rail assembly delivers pressurized fuel supplied from a fuel pump toward intake passages or chambers via associated fuel injectors. The assembly is used to simplify installation of the fuel injectors and the fuel supply passages on the engine.
An ordinary fuel delivery rail assembly having a rectangular section is constructed as shown in FIG. 1 of the attached drawings. In this assembly, an elongated conduit 1 is formed by a steel tube having a rectangular hollow section. To an end of the conduit 1, a fuel inlet pipe 2 for introducing gasoline fuel is secured, and to the other end of the conduit 1, a fuel return pipe 3 leading to an exit for residual fuel is secured, both pipes being welded to the conduit by copper brazing. To the inside of the conduit 1 and the pipes 2, 3, copper plating or nickel plating is coated for protecting the surfaces from rust and for keeping the fuel clean.
The conduit 1 comprises four walls and a fuel passage therein (FIG. 2). To an outside surface of one wall 4, are attached a plurality of sockets 5, the number of which corresponds to the number of combustion cylinders. One end of each socket 5 communicates with the fuel passage 10, and the other end of each socket 5 is so formed as to receive an associated tip of a fuel injector. In most cases, these sockets 5 are inserted into guide holes arranged within the wall 4 of the conduit 1 at predetermined intervals, and welded thereto by copper brazing. The axial directions of the sockets 5 should precisely line up in alignment with the respective axial direction of the injectors. Furthermore, pitch lengths between adjacent sockets should precisely coincide with the corresponding pitch lengths between associated injectors. One of the objects of the present invention is directed to these alignment problems as discussed in detail below.
FIG. 4 shows a conventional connection between a fuel conduit 11 and a socket 15. For producing this kind of metallic socket 15, many kinds of working steps are needed. For example, at first a rough fabrication is made by a forging work, and then it is machined to make a form of an interior surface 16 and a stepped annular portion 17. The annular portion 17 is inserted into a guide hole 18 arranged in the wall 14 of the conduit 11. Then, copper brazing is applied to the abutment surface between the conduit 11 and the socket 15. Therefore, for making the complicated socket 15, many kinds of time-consuming working steps and transferring handling are needed, resulting in an increase of manufacturing cost.
FIG. 5 shows another conventional connection between a fuel conduit 21 and a socket 23, disclosed in Japanese utility model public disclosure No. 40577/1984. In this simple connection, a bottom surface of the socket 23 is secured to a wall surface of the conduit 21 in abutment relation therewith. Apparently, this connection cannot provide a precise alignment between the two parts, since the wall surface of the conduit 21 is not machined. Furthermore, there is no room for adjustment in assembling of the two parts.